Well jet device and the operation method thereof

ABSTRACT

Well jet enables forming, via jet pump, range of different depressions in well tail area at specified differential pressure value. Logging instrument enables recording well and pumped out medium physical parameters. Well operating modes are adjusted by spring-loaded stepped piston positioned in seal unit body so as to open and close holes. Return valves in pumped out and active media supply channels, combined with stepped through channel, of diameter equal to or greater than diameter of the axial through hole of a packer and which is made in the pump body below a mounting seat, enable supplying chemical reagents along a pipe string to a production formation without additional units and prevent media pumped to the production formation, from annular above-packer space penetration. Said invention enables increasing reliability and performance by preventing active medium backflow and by maintaining the depression produced on the formation when the jet pump is stopped.

FIELD OF THE INVENTION

This invention relates to the field of pump engineering and in particular to well jet devices for carrying out logging works.

BACKGROUND OF THE INVENTION

A well jet device is known, which comprises a pipe string with a jet pump and a packer and is capable of pumping an operating fluid through the jet pump (see: RU Patent No. 2059891 C1, F04F 5/02, Oct. 5, 1996).

The same patent teaches a method of operating a well jet device, which includes: installing a jet pump on a pipe string in a well, installing a geophysical instrument in a flow string below the jet pump, lowering the pipe string together with the jet pump, a packer and the geophysical instrument into the well and pumping an operating fluid through the jet pump. The above method of operating a well jet device enables to pump a variety of produced media, e.g., oil, out of a well, while simultaneously treating a produced medium and the formation near-well area, but the possibility of carrying out works on well surveying is limited, which in a number of cases narrows the field of use of this device and the operation method thereof.

In respect of the device, as a subject matter of the invention, the closest to the invention as to the technical essence and the achieved result is a well jet device comprising a pipe string, a packer and a jet pump, in the body of which an active nozzle with a mixing chamber are installed and a through channel with a seat for mounting a sealing unit having an axial channel is made, the output of the jet pump being connected to the pipe string above the sealing unit, the inlet of the jet pump channel for supplying a pumped out medium being connected to the pipe string below the sealing unit, and the inlet of the channel for supplying an operating fluid to the active nozzle is connected to the space surrounding the flow string, and several channels for supplying a pumped out medium being made in the jet pump body (see RU Patent No. 2106540, F04F 5/02, Oct. 3, 1998).

The same patent teaches an operation method as a subject matter of the invention, the closest to the invention as to the technical essence and the achieved result in respect of the operation method, which includes: arranging a packer and a jet pump on a pipe string in a well, the packer being installed over a producing formation, lowering a sealing unit and a logging instrument attached to a cable, and pumping an active operating fluid, e.g., water, into the nozzle of the jet pump through the pipe string annular space, thus reducing pressure in the under-packer area and creating pressure drawdown to the formation, monitoring parameters of the fluid pumped out of the formation during the jet pump operation, and equalizing pressures after stopping the supply of the active operating fluid by a fluid backflow along the jet pump flow-through portion.

The above device and the operation method thereof enable to carry out various process operations in a well below the jet pump installation level, also by reducing a pressure differential above and below the sealing unit. But this device does not enable to use its possibilities to the fullest extent due to the impossibility of maintaining a differential pressure drawdown when the jet pump is not in operation, which does not enable to survey wells completely.

SUMMARY OF THE INVENTION

The objective of this invention is to prevent a spontaneous backflow of an active operating fluid after stopping the jet pump operation, while maintaining a differential pressure drawdown on a formation when the jet pump is not in operation.

The technical effect achieved by this invention consists in improving the reliability and productivity of a well jet device during well testing and optimizing the operational procedure during testing wells.

In respect of the device, as a subject matter of the invention, the stated technical problem can be solved due to the fact that the proposed well jet device comprises a jet pump installed on a pipe string and a packer with an axial passage opening, an active nozzle and a mixing chamber with a diffuser being arranged in alignment in the jet pump body, and the said body also has a stepped through channel with a mounting seat between steps, a channel for supplying a medium pumped out of a well, which communicates below the mounting seat through lateral holes made in the jet pump body to the stepped through channel, and a channel for supplying an active operating fluid, which communicates to the active nozzle on its outlet end and to the pipe string annular space on its inlet end, the channel for supplying a pumped out medium communicating to the pipe string below the stepped through channel via a check valve, and the stepped through channel providing the possibility of installing a sealing unit which is made as a hollow stepped cylindrical housing which upper part comprises a sealing element and below, in the cavity, a stepped piston is arranged, which abuts against a shoulder made in the sealing unit housing and is spring-loaded against the sealing element; holes are made in the wall of the sealing unit housing opposite to the lateral holes made in the jet pump body, and the stepped piston in its lower position closes the holes in the wall of the sealing unit housing, and in the stepped piston upper position the channel for supplying a medium pumped out of a well is communicated to the pipe string below the jet pump body via the lateral holes in the jet pump body and the holes made in the wall of the sealing unit housing; axial channels, which are in alignment, are made in the stepped piston and the sealing element for the purpose of passing a logging cable therethrough which serves for suspending a logging instrument with the use of a cable head and below the jet pump body; a check valve is installed in the channel for supplying an active operating fluid; and the diameter of the stepped through channel below the mounting seat is not less than the diameter of the axial through opening of the packer.

In respect of the method, as a subject matter of the invention, the stated technical problem can be solved due to the fact that the method of operating the proposed well jet device includes: assembling a pipe string by arranging a jet pump and a packer on the pipe string, lowering the whole assembly into a well, releasing the packer, supplying a pressurized hydrofracturing fluid or an acid solution via the pipe string into a producing formation, lowering a sealing unit with the use of a logging cable, together with a logging instrument attached to a logging cable head, installing the sealing unit onto the mounting seat in the stepped through channel of the jet pump, arranging the logging instrument in the producing formation area, registering background values of physical fields, in particular thermal fields, in rocks along the well hole during the said lowering operation, creating differential pressure drawdown onto the producing formation by supplying an active operating fluid to the active nozzle with the use of the jet pump, pumping the hydrofracturing fluid or products of chemical treatment out of the producing formation, and registering, while the jet pump is operated, current values of physical fields in rocks and those of formation fluid coming into the well. During the said registration the logging cable is moved along the well hole, including the producing formation, with the use of the logging cable, then the jet pump is stopped, and the inner cavity of the pipe string above the jet pump together with the annular space above the packer is separated from the inner cavity of the pipe string under the jet pump together with the under-packer space with the use of the check valve installed in the channel for supplying a pumped out medium, thus maintaining a reduced bottomhole pressure and registering a formation pressure-restoration curve with the use of the logging instrument. Then, the logging instrument is lifted up with the use of the logging cable, and the stepped piston is pressed by the cable head from below for moving it up and communicating the well under-packer space to the pipe string inner cavity above the jet pump and the well annular space above the packer via the holes made in the sealing unit housing and the lateral holes made in the jet pump body, thus equalizing pressures above and under the packer, and then the logging instrument together with the sealing unit is moved out of the well.

An analysis of various designs shows that the operation reliability may be improved by increasing the functional capabilities of the proposed device used for testing and developing wells.

It has been found that the above-described set of the well jet device elements enables to organize an operational procedure most efficient for using equipment arranged on the pipe string when carrying out logging works on surveying, testing and developing producing formations in rocks. It also creates conditions both for obtaining full and reliable information on producing formations and for carrying out treatments of producing formations during a survey. The proposed well jet device enables to create several differential pressure drawdown values at a given differential pressure by using a jet pump in the under-packer area of a well, and use a logging instrument for registering pressure, temperature and other physical parameters of a well itself and a medium pumped out of it, surveying and testing a well, and register a formation pressure-restoration curve in the under-packer space of a well without using a special functional insert. However, in a number of cases where only a survey is conducted or a producing formation is treated with the use of a logging instrument, e.g., in a case of treating a producing formation with physical fields, in particular with ultrasound, it is insufficient for intensifying an inflow from a producing formation.

Providing the well jet device with check valves in the channels for supplying an active operating fluid and a pumped out fluid, in combination with making the diameter of the stepped through channel below the mounting seat not less than the diameter of the axial through opening of the packer, enables to supply chemical reagents or a hydrofracturing fluid via the pipe string without using any additional tools or functional inserts on the pipe string and improve the work efficiency, wherein the check valves prevent media pumped into a producing formation from entering into the well annular space above the packer during pumping operations. The above-said relation between the diameters of the stepped through channel and the axial through opening of the packer is very important. Making the diameter of the stepped through channel not less than the diameter of the axial through opening of the packer is necessary for obtaining the possibility of lowering a logging instrument into the well under-packer area for the purposes of treating a formation with physical fields (treating with ultrasound or creating, e.g., a thermal field) and reducing hydraulic resistance both when pumping various media into a producing formation and for pumping a produced medium out of a producing formation after a differential pressure drawdown on such a producing formation is created. At the same time, it becomes possible to monitor a differential pressure drawdown value by controlling the rate of supplying an active operating fluid. During testing formations it is possible to adjust pumping modes by changing the pressure of an active operating fluid supplied to the active nozzle of the jet pump. Also, a spontaneous backflow of an operating fluid into the under-packer area is precluded both when the jet pump is operated and is not operated.

The result is intensification of works on surveying and developing wells, which enables to carry out surveying and testing wells after drilling and during overhauling with good quality, and prepare well for operation by comprehensively surveying and testing then in different modes, thus improving the reliability of well jet device operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section of the proposed well jet device without a sealing unit and a logging instrument.

FIG. 2 shows a longitudinal section of the proposed well jet device with a sealing unit and a logging instrument that are arranged in the area of a producing formation.

FIG. 3 shows a longitudinal section of the proposed well jet device during preparing it for lifting up a logging instrument and a sealing unit to the surface.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The proposed well jet device comprises a jet pump 2 and a packer 3, which are arranged on a pipe string 1, an active nozzle 5 and a mixing chamber 5 with a diffuser being installed in alignment in the body 4 of the jet pump 2, the said body also includes a stepped through channel 7 with a mounting seat 8 between steps, a channel 9 for supplying a medium pumped out of a well, which is connected via lateral holes 10 made in the body 4 of the jet pump 2 to the stepped through channel 7 below the mounting seat 8, and a channel 11 for supplying an active operating fluid, which is connected on its outlet end to the active nozzle 5 and on its inlet end to the annular space around the pipe string 1. The channel 9 for supplying a pumped out medium is connected via a check valve 12 to the pipe string 1 below the stepped through channel 7, the latter providing the possibility of installing a sealing unit 13 made as a hollow stepped cylindrical housing 14 which upper part is used for arranging a sealing element 15, and a stepped piston 17, which is spring-loaded against the sealing element 15, is arranged below the sealing element 15 in the housing 14 of the sealing unit 13. Holes 19 are made in the housing 14 of the sealing unit 13 opposite to the lateral holes made in the body 4 of the jet pump 2. The stepped piston 17 in its lower position closes the holes 19 in the housing 14 of the sealing unit 13 and in its upper position the channel 9 for supplying a pumped out medium is connected via the lateral holes 10 in the housing 4 of the jet pump 2 and the holes 19 in the housing 14 of the sealing unit 13 to the pipe string 1 below the body 4 of the jet pump 2. Aligned axial chambers for passing through them a logging cable 20 are made in the stepped piston 17 and the sealing element 15, and a logging instrument 22 is suspended on the cable 20 below the body 4 of the jet pump 2 with the use of a cable head 21 in such a way that the instrument 22 may be moved along a well and be disposed in the area of a producing formation 23. A check valve 24 is installed in the channel 11 for supplying an active operating fluid; the packer 3 is provided with an axial through opening 25; and the diameter d of the stepped through channel 7 below the mounting seat 8 is less than the diameter D of the axial through opening 25 in the packer 3.

The operation method of the proposed well jet device can be carried out as follows. The pipe string 1 is assembled by installing the jet pump 2 and the packer 3 on the pipe string 1. The assembly is lowered into a well, and the packer 3 is released. A hydrofracturing fluid or an acid solution is supplied under pressure via the pipe string 1 to the producing formation 23, and the sealing unit 13 is lowered into the well on the logging cable 20 with the logging instrument 22 attached to the cable 20 through the cable head 21. The sealing unit 13 is installed on the mounting seat 8 in the stepped through channel 7 of the jet pump 2, and the logging instrument 22 is arranged in the area of the producing formation 23. During the lowering operation the logging instrument 22 is used for registering background values of physical fields, in particular thermal fields, in rocks along the well hole. Then, the hydrofracturing fluid or products of chemical treatment of the producing formation are pumped out of the producing formation 23 by the jet pump 2 by supplying an active operating fluid through the annular space around the pipe string 1 and into the active nozzle 5. After that, when the jet pump 2 is operated, current values of physical fields in rocks and a formation fluid coming into the well are registered, and during such registration the logging instrument 22 is moved along the well hole, including the producing formation 23, with the use of the logging cable 20,

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23. Then, the jet pump 2 is stopped, and the inner cavity of the pipe string 1 above the jet pump 2 with the annular space above the packer 3 is separated from the inner cavity of the pipe string 1 below the jet pump 2 with the under-packer space by using the check valve 12 in the channel 9 for supplying a pumped out medium, thus maintaining a reduced bottomhole pressure and registering a formation pressure restoration curve under the packer 3 by using the logging instrument 22. Then, the logging instrument 22 is lifted up with the use of the logging cable 20, and the stepped piston 17 is pressed from below by the cable head 21 for moving the piston up, thus communicating the well under-packer space to the inner cavity of the pipe string 1 above the jet pump 2 and the well annular space above the packer via the holes 19 in the housing 14 of the sealing unit 13 and the lateral holes 10 in the body 4 of the jet pump 2, thus equalizing pressures above and under the jet pump 2, and then the logging instrument 22 with the sealing unit 13 are moved out of the well.

INDUSTRIAL APPLICABILITY

The proposed invention may be used in the oil and gas industry for developing wells after drilling or during logging operations in any types of wells. 

1. A well jet device comprising: a jet pump and a packer with an axial passage opening that are installed on a pipe string, an active nozzle and a mixing chamber with a diffuser being arranged in alignment in the jet pump body, and the said body also has a stepped through channel with a mounting seat between steps, a channel for supplying a medium pumped out of a well, which communicates below the mounting seat through lateral holes made in the jet pump body to the stepped through channel, and a channel for supplying an active operating fluid, which communicates to the active nozzle on its outlet end and to the pipe string annular space on its inlet end, the channel for supplying a pumped out medium communicating to the pipe string below the stepped through channel via a check valve, and the stepped through channel providing the possibility of installing a sealing unit which is made as a hollow stepped cylindrical housing which upper part comprises a sealing element and below, in the cavity, a stepped piston is arranged, which abuts against a shoulder made in the sealing unit housing and is spring-loaded against the sealing element; holes are made in the wall of the sealing unit housing opposite to the lateral holes made in the jet pump body, and the stepped piston in its lower position closes the holes in the wall of the sealing unit housing, and in the stepped piston upper position the channel for supplying a medium pumped out of a well is communicated to the pipe string below the jet pump body via the lateral holes in the jet pump body and the holes made in the wall of the sealing unit housing; axial channels, which are in alignment, are made in the stepped piston and the sealing element for the purpose of passing a logging cable therethrough which serves for suspending a logging instrument with the use of a cable head and below the jet pump body; a check valve is installed in the channel for supplying an active operating fluid; and the diameter of the stepped through channel below the mounting seat is not less than the diameter of the axial through opening of the packer.
 2. A method of operating the well jet device, including: assembling a pipe string by arranging a jet pump and a packer on the pipe string, lowering the whole assembly into a well, releasing the packer, supplying a pressurized hydrofracturing fluid or an acid solution via the pipe string into a producing formation, lowering a sealing unit with the use of a logging cable, together with a logging instrument attached to a logging cable head, installing the sealing unit onto the mounting seat in the stepped through channel of the jet pump, arranging the logging instrument in the producing formation area, registering background values of physical fields, in particular thermal fields, in rocks along the well hole during the said lowering operation, creating differential pressure drawdown onto the producing formation by supplying an active operating fluid to the active nozzle with the use of the jet pump, pumping the hydrofracturing fluid or products of chemical treatment out of the producing formation, and registering, while the jet pump is operated, current values of physical fields in rocks and those of formation fluid coming into the well; then during the said registration the logging cable is moved along the well hole, including the producing formation, with the use of the logging cable, then the jet pump is stopped, and the inner cavity of the pipe string above the jet pump together with the annular space above the packer is separated from the inner cavity of the pipe string under the jet pump together with the under-packer space with the use of the check valve installed in the channel for supplying a pumped out medium, thus maintaining a reduced bottomhole pressure and registering a formation pressure-restoration curve with the use of the logging instrument; then, the logging instrument is lifted up with the use of the logging cable, and the stepped piston is pressed by the cable head from below for moving it up and communicating the well under-packer space to the pipe string inner cavity above the jet pump and the well annular space above the packer via the holes made in the sealing unit housing and the lateral holes made in the jet pump body, thus equalizing pressures above and under the packer, and then the logging instrument together with the sealing unit is moved out of the well. 